This invention relates to a testing monitor useful for detection of peroxidase-like activity and, in particular, a test kit for detection of such activity in stool samples containing a testing monitor.
The detection of peroxidase-like activity was found to be indicative of the presence of hemoglobin in a specimen and, reported to be correlated to the heightened fertility period in females during the estrous cycle. The detection of peroxidase-like activity has, therefore, become an invaluable aid to the medical practitioner.
Over 100,000 persons in the United States are affected by cancer of the colon and rectum each year. When the number of colorectal cancers occurring each year is combined with the number of cancers occurring in other digestive organs, including the esophagus and stomach, such cancers of the digestive system account for more occurrences of cancer than any other single form of the disease.
Contrary to many other forms of cancer, early diagnosis and treatment of digestive tract cancer results in the cure rate of 80 to 90% of those affected. This cure rate drastically decreases as cancer reaches its later stages. Thus, early detection of the disease is critical to successful treatment.
Most, but not all cancers of the digestive tract bleed to a certain extent. Blood found in the gastric contents and in vomitus is indicative to conditions associated with disorders of the mucous membrane, such as ulcers, diverticulitis, colitis and carcinoma. In addition, blood is also deposited in fecal matter extruded frm the digestive system. The presence of blood in fecal matter is not normally detected, however, until gross bleeding occurs. When this is evident, digestive tract cancers are in their advanced stages.
Various test equipment and procedures have been developed for use by physicians in testing for the presence of occult blood in fecal matter. One of the most successful tests is manufactured and held by Smith Kline Diagnostics of Sunnyvale, Calif. under the trademark "Hemoccult." The package for the Hemoccult test is disclosed in U.S. Pat. No. 3,996,006 issued to J. Pagano. Briefly, the Pagano test employs an absorbent white paper impregnated with a guaiac reagent and encased in a special test slide having openable flaps on both sides. To use the Pagano test slide, one must obtain a sample for fecal matter, smear it onto the guaiac-impregnated paper by opening the panel on one side of the test slide, and then close the panel. A panel on the opposite side of the test slide is then opened and contacted with a developing agent. The developing agent is a stabilized solution of hydrogen peroxide and denatured alcohol which is applied to the guaiac-impregnated paper. If occult blood is present in the fecal matter smeared on the opposite side of the paper, the product of the guaiac reaction will appear as a blue substance against the white paper background, providing a positive indication of the presence of blood in the fecal matter. The Pagano test is designed for evaluation by a diagnostic laboratory. As a test which can be evaluated at home, the Pagano test has two short comings. First, it requires the person to handle fecal matter and secondly, it requires the tester to be somewhat sophisticated when interpretating the results.
There is another problem inherent in the Pagano test and other tests which require laboratory interpretation. This problem relates to the difference in time between the taking of the sample and its evaluation. Of course, there is the obvious problem of storing the test kit after the sample has been taken and, since it is desirable to minimize the premature decomposition of the reactants, the sample must be kept cold. Refrigerator storage of fecal samples is obviously unpopular when the refrigerator storage space must be shared by food utilized by the consumer.
A more serious problem with clinical tests is disclosed in "Gastroenterology 1982"; 1982-986-91 in which it is stated that prolonged storage in desiccation can affect the reliability of the guaiac-impregnated slide test in detecting fecal occult blood. The reliability of the test is related to hemoglobin concentration; a slightly positive reaction can become negative upon storage and a test yielding strong positivity for blood can convert to less pronounced or even ambiguous results. The exact reason for this apparent time dependent conversion is not known, although it is assumed that the denaturation of hemoglobin in stool by proteolytic enzymes and bacteria occurs. It has been shown by this reference that a concentration of hemoglobin and stool may produce a very strong positive reaction which is stable for thirty days whereas a weak positive response will become negative on the sixth day after specimen application. For these reasons, it is apparent that a test which can be conducted reliably by the individual in this own home and which can yield readily discernably results is the test method of choice.
A non-clinical test is disclosed by D. E. Fonner in U.S. Pat. No. 2,838,377. The Fonner test utilizes O-tolidine and benzidine. The reagents when mixed with blood and other reactants produce a visible dye. The Fonner test employs a testing apparatus which can be dropped into the toilet bowl. The Fonner test has, however, not been particularly successfully because of the high rate of false positive indications associated with it.
The ideal test, therefore, should be one which can be conducted as an in-house test with monitors to eliminate false positive or false negative readings. Also the test should be designed to eliminate the manual handling of stool samples or stool sample-contaminated testing matrixes.
U.S. Pat. No. 4,175,923 issued to William G. Friend discloses a test which utilizes a test strip which is dropped in the toilet bowl. A portion of the test strip contains blood which will react with the other components of the test coating, e.g., guaiac and peroxide to produce the blue color which is characteristic of a positive test for occult blood and, therefore, provides the user with a ready frame of reference for the color change associated with a positive test.
U.S. Pat. No. 3,323,710 issued to P. Rieckmann et al. discloses the use of a strip having a sealed preprinted color indicator comparison test area for ready comparison when a color indicator test is performed.
U.S. Pat. No. 4,365,970 issued to Paul J. Lawrence et al. describes a occult blood test with apparatus similar to that disclosed in Pagano and Friend having, in addition, built in positive and negative performance monitors in the form of two small spots. One of these spots contains a blood component. The other spot is guaiac treated paper. When the developer solution is applied to the spot containing the blood component its color change indicates that the developer solution is efficacious. If there is a color change present from the addition of the developer solution to the negative control, there is a defect in the test paper which destroys the efficacy of the test.
U.S. Pat. No. 4,541,987 issued to P. A. Guadagno discloses an in-bowl toilet test with a so-called positive control site employing the test reagent, a peroxygen compound and a small amount of catalyst that would always yield positive results. If no color change occurred in this control area when the area was wet, the test would be shown to be defective. A second control is also disclosed which is an area containing only the peroxygen composition. According to this patent, a color change at this area would indicate a contaminant in the pad, or improper manufacture. This analysis is only true if the paper inherently has a substitute for both haem and oxygen sensitive dye. While this is disclosed as a test for toilet bowl contamination, it would not produce a color change with residual strong oxidants only.
U.S. patent application No. 491,008 entitled "Specimen Collection Wipe for Occult Blood Detection" filed May 3, 1983 assigned to the assignee of the invention and subject to a notice of allowance also discloses the concept of an indicator activity verification region which changes color to monitor the efficacy of the testing reagent. A neutral response region is also provided to eliminate the possibility of false positives due to contamination of the paper.
While the prior art test comparison verification procedures are beneficial toward increasing the efficacy of the readings of the results of these tests, none of these tests monitor the presence of pre-existing contaminants in the toilet bowl water. Strong oxidizing agents are routinely used to clean toilet bowls and tend to contain compounds such as hypochlorites for their function as a bleaching agent. These and other strong oxidizing agents may provide oxidative residues which produce a false positive test.